POS0665 DEVELOPMENT OF A BIOCHEMICAL TOFACITINIB ADHERENCE ASSAY IN RHEUMATOID ARTHRITIS: THE ORAL ADHERE STUDY
Authors: S. Church, K. Hyrich, K. Ogungbenro, R. Unwin, A. Barton, J. Bluett
Journal: Annals of the Rheumatic Diseases (2022)

Background Tofacitinib is a potent inhibitor of the JAK1/JAK3 tyrosine kinases effective in the treatment of rheumatoid arthritis (RA). Unlike biologic DMARDs, tofacitinib is administered orally. Oral administration offers a major benefit to patients, removing the risk of injection site reactions and previous research has shown that patients prefer an oral DMARD which may affect patient’s adherence (1). Non-adherence is a health behaviour that results in reduced response and increased healthcare costs but can be challenging to accurately measure. Direct tofacitinib measurement may be an accurate measure of adherence that could, in the future, be used in a clinical setting as part of a behaviour change intervention. Tofacitinib can be measured using High Performance Liquid Chromatography Selected Reaction Monitoring Mass Spectrometry (HPLC-SRM-MS). Previous tofacitinib studies have demonstrated an assay sensitivity of 0.1ng/ml may be sufficient for the detection of adherence following 5mg twice daily administration (2). Objectives The aim of this study is to develop a HPLC-SRM-MS assay to measure biochemical tofacitinib adherence in patients with RA. Methods Human serum for method development was obtained from volunteers recruited to the collection of blood and urine samples from volunteers for the development of analytical methods study (UREC 12346) and the National Repository Study (REC 99/8/84) following informed consent. Samples were spiked with Tofacitinib/Tofacitinib-d3 and subjected to protein precipitation. LC-MS/MS analysis was performed on a TSQ Vantage triple quadrupole mass spectrometer coupled with an Accela UHPLC system (Thermo Fisher Scientific, USA). Validation of the assay was tested as adapted from European Medicines Agency guidelines on Bioanalytical Validation. Specifically, the lower limit of quantification (LLOQ), carryover, accuracy, linearity, precision, recovery and stability of the assay was determined. To investigate the ability of the assay to detect adherence, serum samples (n=10) of patients prescribed tofacitinib from the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate (BRAGGSS) were analysed (REC reference: 04/Q1403/37). Participants self-reported date and time of tofacitinib ingestion prior to venepuncture. Samples were analysed in triplicate. Results The assay demonstrated a tofacitinib LLOQ of 0.1ng/ml, carryover of sample following injection of a 1000 ng/ml tofacitinib was &lt;1%, linearity of r2=0.998, within run accuracy was between 81-85% at LLOQ and between 91-107% at all other levels. Between run accuracy was within 14.9% at LLOQ and within 0.2-5.1% of the nominal concentration at all other levels. Samples of tofacitinib spiked in whole blood and left at room temperature for seven days were within 0.98-10.25% of serum samples spiked on the day of analysis for all concentrations. To demonstrate the potential of the assay to determine adherence, all 10 BRAGGSS samples revealed tofacitinib levels above 0.1ng/ml with CV&lt;15% (Table 1). Table 1. Sample ID Time difference between self-reported tofacitinib ingestion and blood sample (hours) Mean Tofacitanib (ng/ml, n=3) CV (%) 49 7.0 26.43 2.82 40 2.8 100.55 5.51 70 3.6 73.23 2.27 68 1.5 150.37 8.09 20 1.5 137.46 9.09 30 1.8 117.85 14.97 33 1.4 90.89 1.18 79 5.4 217.47 11.40 17 2.8 108.43 7.43 37 2.5 335.04 3.48 Conclusion A novel tofacitinib LC-MS/MS assay has been developed. The ability of the assay to measure biochemical adherence has been explored. Further research to establish the sensitivity of the assay and the ability of the assay to detect non-adherence are required. References [1]Alten R, Krüger K, Rellecke J, Schiffner-Rohe J, Behmer O, Schiffhorst G, et al. Examining patient preferences in the treatment of rheumatoid arthritis using a discrete-choice approach. Patient Prefer Adherence. 2016;10:2217-28. [2]Suzuki M, Tse S, Hirai M, Kurebayashi Y. Application of Physiologically-Based Pharmacokinetic Modeling for the Prediction of Tofacitinib Exposure in Japanese. Kobe J Med Sci. 2017;62(6):E150-E61. Acknowledgements Financial support was provided as an Investigator Sponsored Research Grant from Pfizer Limited Disclosure of Interests Stephanie Church Grant/research support from: Financial support was provided as an Investigator Sponsored Research Grant from Pfizer Limited, Kimme Hyrich Speakers bureau: Honoraria as a speaker received from Abbvie, Grant/research support from: Financial support was provided as an Investigator Sponsored Research Grant from Pfizer Limited. Research grant award from BMS, Kayode Ogungbenro Consultant of: Afferent, Biogen, Buzzard, Grant/research support from: Financial support was provided as an Investigator Sponsored Research Grant from Pfizer Limited., Richard Unwin Grant/research support from: Financial support was provided as an Investigator Sponsored Research Grant from Pfizer Limited, Anne Barton Grant/research support from: Financial support was provided as an Investigator Sponsored Research Grant from Pfizer Limited. AB has received grant funding from Scipher Medicine Ltd, Bristol Myers Squibb and Galapagos in the past 12 months., James Bluett Grant/research support from: Financial support was provided as an Investigator Sponsored Research Grant from Pfizer Limited. JB has received travel/conference fees from UCB, Pfizer and Eli Lilly